Radiation “Awareness”
Objectives
• To increase public understanding of
radiation and radioactivity
• To provide basic radiation-science
information for use by science teachers
Health Physics Society
Specialists in Radiation Protection
Outline
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Radiation theory & basics
Exposure and effects
Ways to minimize exposure
Beneficial uses in modern society
Resources and additional information
Why Are Elements
Radioactive?
Unstable nucleus:
• Has excess energy.
• Wants to go to
“ground state.”
• Becomes stable by
emitting ionizing
radiation.
What does “ionizing” mean?
Who Discovered
Radioactivity?
Antoine Henri Becquerel
• Worked with uranium.
• Noticed phosphorescence
caused film exposure after
leaving uranium in the
sun.
• Noticed same thing
happened on cloudy days.
Radiation Types
Alpha Particles
(2n, 2p)
Beta Particles
(e-or+)
Photons (hv)
(x or gamma rays)
Paper
Concrete
Ionizing Radiations
Beta Decay
3H
Beta
particle
3He
NN
P
N
e
e
Anti
Neutrino
PP
Ion
The Electromagnetic Spectrum
Figure courtesy of NASA/JPL-Caltech
Ionizing Radiations
Gamma Emission
137mBa
137Ba
Gamma ray
Excited
Nucleus
Definitions
• Radioactive decay is a spontaneous process in which
nucleons are emitted from or transformed within the
nucleus, resulting in a change in the identity of the
nucleus, and usually accompanied by the emission of
one or more types of radiation from the nucleus and/or
atom.
• Half-life is the time required for half of the atoms of a
radioactive material to decay to another nuclear form.
Who’s the Famous “Madame” of
Radiological Fame?
Marie Curie
• With her husband
Pierre, discovered
radium and coined
the term
“radioactive”
• First woman to win
two Nobel Prizes
Units of Radioactivity
• The becquerel (Bq)
or
• The curie (Ci)
1 Ci = 37,000,000,000 Bq
so 1 mCi = 37 MBq
and 1 µCi = 37 kBq
Approximate Radioactivity
in Assorted Items
Item or Process
mCi
MBq
0.001
0.037
• Biomedical Lab Experiment
0.5
18.5
• Nuclear Medicine Dose
10
370
• Smoke Detector
• Industrial Radiography Source 40,000
1,480,000
Natural Background Radiation
Man-Made Radiation
Biological Effects
Mechanisms of Injury
Ionizing Radiation
Cell Damage
Repair
Transformation
Cell Death
Radiation Dose
Dose or radiation dose is a generic term for a
measure of radiation exposure. In radiation
protection, dose is expressed in millirem.
External Dose
After
X-Ray
Machine
Image
(film)
Subject is not radioactive but
has been exposed to a
radiation dose (single chest x
ray = 5-10 mrem).
Contamination
Contamination is the presence of a radioactive
material in any place where it is not desired,
and especially in any place where
its presence could be harmful.
Yuck!
Radiation Detection Instruments
Photo by Carl Tarantino
Geiger Counter
Photo by Karen Sheehan
Liquid Scintillation Counter
Lessons from the Past
The Radium Dial Painters
Photo by Carmelina Rattrovo from the Playwrights Theatre production of Radium Girls, by D.W. Gregory
Annual Radiation Dose Limits
General Public vs. Occupational
Established by the
Nuclear Regulatory Commission
• General Public Limit - 100 mrem
• Occupational Limit - 5,000 mrem
Remember – We get approximately 300 mrem per
year from natural background exposure.
Minimizing Radiation
Exposure
Basic Concepts
• Time
• Distance
• Shielding
Minimizing Exposure - Time
• Minimize the
amount of time
spent near
sources of
radiation.
Minimize Exposure by
Maximizing Distance
As the distance from a radioactive
source doubles, the exposure rate
decreases by a factor of four.
Minimizing Exposure By
Using Shielding
Lead blanket
shielding around
letdown radiation
monitors
Surry Power Station
Loss of Life Expectancy
Activity or Behavior
LLE (DAYS)__________________
Recreational swimming
40
Being 15 percent overweight
900
Smoking 20 cigarettes per day
1,600
Using pesticides at home
12
Being exposed to radon in a home
35
Living within 10 miles of a nuclear power plant
0.4
Riding a bicycle
6
Driving a car
200
Skydiving
25
Consuming alcohol (U.S. average)
230
Medicine and Research
• Colleges
• Doctors’ Offices
• Hospitals
• Pharmaceutical
• Research and Development
Research: As a “Tracer”
• Radioactivity is an excellent
tool!
• Detectable in minute quantities
(like finding one grain of sand
on a small beach containing
6,000,000,000 granules)
Power Generation
Nuclear power
supplies 20 percent
of energy in the
United States.
There are 104
nuclear power
plants in the United
States.
Photo by Karen Sheehan
Space Exploration
The fuel in:
• Satellites
• Jupiter Probe
• Others
Jupiter Probe
Who Discovered X Rays?
Wilhelm Conrad
Roentgen
Roentgen worked with a
Crookes tube to study
cathode rays.
How X Rays Work
X Rays (continued)
Other Types of X-Ray Machines
Photos by Karen Sheehan
X-Ray Crystallography
Photo by Karen Sheehan
Nuclear Medicine
Diagnostic Procedures
• Radioactive injection
• Short half-life
radionuclide
• Pictures taken with
special gamma camera
• Many different studies:
Thyroid
Lung
Cardiac
White Blood Cell
Photo by Karen Sheehan
Bone Scans
Image courtesy of
Radiation Therapy
Used for treating cancer. Why does it work?
Photo by Karen Sheehan
Image courtesy of
External Beam
Brachytherapy (implants)
Radioactive Consumer Products
Photo by Karen Sheehan
For more information
about radiation you may
contact the Health
Physics Society.
http://www.HPS.org
Health Physics Society
Specialists in Radiation Safety
Additional References
• Hall E. Radiation and life, 2nd ed.
New York: Pergamon Press; 1984.
• Bushong SC. Radiologic science for
technologists, 7th ed. St Louis, MO:
Mosby, Inc.; 2001.